Seems the relief workers may just be desperate to get the aid to the suffering, at any rate. Seems like a lot of rain as well. Maybe one big parachute with a lot of boxes attached would be more practique...

Keep an eye on the next "Shining Star Path" CCTV's American Idol. It will have a pretty cool Uigher act on it, though he is kicked out in the second round, after getting our whole section dancing.

@SittingHere: When is that going to be on TV? Which CCTV station?

I think you calculation is barely correct because you neglect the air resistance. For a good estimate you need the size and the weight of the boxes. A box filled with instant noodles will be a lot slower than a box filled with bottles of water. And by looking at the video I have the feeling the boxes have been quite light for their size. So I would say the chances are good that they survived the impact.

@Ansiwen: Actually, weight has nothing to do with speed. Remember the legend of Galileo's experiment. Dropping two balls of different weight off the Leaning Tower of Pisa -- both hit the ground simultaneously. This is because acceleration is, to a first approximation, constant. Higher mass = higher force of gravity = same acceleration because the mass is divided out.

However, kinetic energy does depend on mass, so it does play a role in the amount of dissipated energy when they hit. Actually, the area looks fairly waterlogged. Water allows an object to slow down over a longer distance, and therefore receive less force. There are several recorded instances of pilots surviving falls after failed parachutes, by having the good luck to land in deep snowdrifts or lakes.

Rule of thumb for skydivers is that terminal velocity is approximately 120 mph (200 kph), due to air resistance. And, mind you, humans are more aerodynamic than rectangular boxes, even if you put them on the edge.

Ignoring air resistance, a free object falling from height H will gain speed v (m/s) when hitting the ground:
v=sqrt(2Hg)
The height was 50m according to the conversation in the video, so
v=sqrt(2*50*9.8)=31m/s

If the duration of the drop was 5 sec, the distance dropped would be .5*9.8*5*5 (s = vt+0.5*gt^2) which is 122.5 m. That's over 30 storeys high.

but god forbid you should be the point of impact for one of those boxes. imagine surviving the earthquake and then being squashed by the relief.

I was wondering the same thing when I saw that, plus worried that people might get hit by 50lbs of Nestle spring water. My first thought was since they're in a chopper, why not select certain drop zones and hover in low and toss out 10 or so boxes then move to the next drop. It looked a bit crazy the way they were doing it. A lot of that ground below looked waterlogged or swampy as well.

During WW2 the Aussies in Papua new Guinea developed a "biscuit bomber" supply drop service for troops without using parachutes. They found that supplies were smashed when dropped even at low speed and low level. The answer was to pack them in two loose boxes - the outer one was destroyed but dissipated the force, leaving the inner one intact.

I have to disagree with "Scientist". For the same shape and size, weight or mass(m) DOES play an important role in terminal speed v (resistance(v) = mg) and acceleration (a = g - (resistance force)/m). Consider this: a man may use parachute to land safely with slow enough terminal speed. Now imagine you drop a tank using the same parachute, it would crash into pieces. A tank needs a much bigger parachute to get the same terminal speed.

Maybe it makes for more dramatic television than landing and handing out stuff to disaster ravaged people.

Maybe it's more efficient and safer? The helicopters can make more trips to distribute supplies to more towns. Also, landing in unfamilia rain soaked land may not be safe. BTW, they'd do this with or without the reporter on board. I think they were too busy trying to save people to think about photo ops. What did you do for the disaster ravaged people? I guess nothing?

Mick made a good point. I used to be in the Aust. Army and I was also a paratrooper...I've seen a few things fall from the sky when they shouldn't have... bottled water smacks like a watermelon... but... put a couple together and it bounces like a bouncy ball (the first couple taking the brunt of the impact)

MyTake,

Ignoring air resistance, the terminal speed has nothing to do with the mass/weight/shape of the object. The reason that you need a much bigger parachute to for a tank is that the gravity for a tank is much bigger for a man. To counter-act on the gravity, you need a much bigger parachute to generate a much stronger air resistance force.

Ignoring air resistance, the terminal speed of a tank and a man falling from the same height is the same.

My random, uniformed guess:

Chinese government aid workers have to meet quotas of x amount of aid given. To give more aid means a more favorable report, so in order to give aid faster (and meet quotas), some aid workers choose to (or are forced to) simply drop aid and mark it down as "distributed".

The wide range of responses to this thread is indicative of the broad readership ( correct word/phrase?) this blog in fact has - ah the silent majority are there tho not always vocal. A Good point to remember.

May 12, 2008
Earthquake in Sichuan Province
Interactive map showing the extent of the most damaged areas from the 7.9 magnitude earthquake in Western China.

http://www.nytimes.com/interactive/2008/05/12/world/05132008_CHINA_MAP.html#

As God is my witness, I thought Turkeys could fly.

@michael
Supposedly the Uighur singer will be on Chinan Idol on:
5月27日中午12：30 CCTV-3
5月31日中午12：30 CCTV-3
6月1日下午17：10 CCTV-3

The lack of physics knowledge is rather impressive.
@michaelmanning
the velocity of the helicopter would probably play a minimal role in the impact velocity of the boxes for two reasons, one is that the forward velocity will be significantly reduced by wind resistance, and the damage is done only by the component of the velocity the is perpendicular the ground, the normal. in other words, the velocity of the box moving forward does very little to increase the force with which it hits the ground.

@CC
"Ignoring air resistance, the terminal speed of a tank and a man falling from the same height is the same."
Yes, I guess thats true in a sense, since without air resistance the terminal velocity is infinite. Terminal speed is determined by the mass and the drag coefficient as well as the viscosity of the medium through which an object is traveling. If you drop a tank and a man from the same height in a vacuum you are right, they will hit the ground at the same time but it wont be at terminal velocity since there is no terminal velocity in a vacuum.

@Scientist
You are completely wrong, with modern equipment, we can see that two bowling balls of different masses and the same shape will not hit the ground at the same time, due to air resistance, which acts as an opposing acceleration which increases proportionally to velocity until it counteracts the acceleration due to gravity. Since two equally shaped bowling balls with have the same drag coefficient but the higher mass of one will give it more force to push through air.